Dionicio Castellanos Torres is a Mexican pro wrestler (best known by the stage names Psychosis or Psicosis) currently performing as Nicho El Millionaro in Consejo Mundial de Lucha Libre. He is a two-time WCW Cruiserweight Champion and has performed for WWE, ECW Asistencia Asesoria y Administracion, TNA Wrestling, and Xtreme Pro Wrestling.

Castellanos started wrestling as Psicosis for the Asistencia Asesoria y Administracion promotion in his native Baja California in March 1989, after being trained by Rey Misterio, Sr. and his brother, Fobia. Some of his biggest feuds were with Rey Mysterio and El Hijo del Santo. He frequently feuded with La Parka although he would team with him later in WCW, Juventud Guerrera and Juvi's father, Fuerza Guerrera. Also, he appeared in the movie/documentary "101 Reasons Not To Be A Pro Wrestler".

Psicosis first made a name for himself in the United States in joining ECW in 1995.

He then switched to WCW as Psychosis in 1996. His Nitro debut match took place at WCW Monday Nitro July 8, 1996 against Eddie Guerrero during WCW's tour of Disney MGM Studios. Through the early years, Psychosis would typically face other luchadores, frequently getting a spot during Pay-Per-View events. He faced La Parka at Spring Stampede March 19, 1998 a match in which he won. Many people don't know (mostly because WCW never acknowledged it) that Psychosis was actually a member of the nWo in Konnan's Promo Azteca. Other members included Rey Misterio (not to be confused with Rey, Jr.) and Holloween/Ciclope.

In 1999, Psychosis joined Eddie Guerrero's Latino World Order (LWO). The group, made up entirely of Mexican wrestlers, would be disbanded at the hands of the nWo shortly after.

Later in his career, Psychosis was frequently managed by Sonny Onoo and had a regular tag team with La Parka. Psychosis originally lost his mask to Rey Misterio, Jr. during a tour of Mexico. Psychosis removed the mask and handed it to Rey, Jr. while simutanously covering his face with a towel. The reason for this was that Psychosis was not supposed to lose his mask. He would later go on to lose his mask to Billy Kidman on an episode of Nitro. On occasion, he was also paired with Juventud Guerrera. When Guerrera won the IWGP Junior Heavyweight Title on WCW TV and then got injured, Vince Russo stripped Guerrera and had Psychosis and La Parka go for the vacant title, which Psychosis won. He then lost it to Jushin Liger the same night.

During the April 19, 1999 edition of WCW Monday Nitro, Psychosis defeated Blitzkrieg, Juventud Guerrera, and Rey Mysterio in a 4-way bout to win the WCW Cruiserweight Championship for the first time. This reign would be short-lived, however, as he would lose it to Rey Mysterio not long after.

On September 27, 1999, Psychosis competed in a máscara contra caballera (mask vs. hair) match against Billy Kidman. Kidman won, and like both Juventud Guerrera and Rey Mysterio before him, Psychosis was forced to unmask.

Psychosis had a second, rather forgettable Cruiserweight Title reign in WCW. When the previous champion Lenny Lane (who portrayed a flamboyant homosexual on television) got WCW in hot water with the GLAAD, Lane was pulled from television. Psychosis was given the belt only to lose it to Disco Inferno.

Psychosis left WCW before the sale to the WWE owner and chairman Vince McMahon and was part of the short-lived Xtreme Wrestling Federation, wrestled in World Wrestling All-Stars and also for All Japan Pro Wrestling. He also made a brief return to ECW as well, competing there from July-November 2000. The highlight of his second run was an incredible match with Yoshihiro Tajiri at the ECW Arena. Psychosis was also part of "La Familia" with Konnan, Juventud Guerrera, Halloween and Damien in Xtreme Pro Wrestling, an adaptation of the group in Mexico consisting of himself, Halloween, Damien 666 and Rey Misterio, Sr.

Psychosis had a dispute with TICKLE in Mexico which held the rights to his ring name, so he switched it to Nicho El Millonario and continued to work in Mexico, mostly in Tijuana with occasional dates in the United States and Consejo Mundial de Lucha Libre. In 2005, he returned to AAA to feud with a wrestler by the name of El Leon Negro who assumed the name "Psicosis" when he originally left the promotion. The two had a "name vs. name" ladder match at Triplemania XIII but Histeria ran in and took the name for himself so the feud evolved into a three way feud.

Psicosis made a few appearances for TNA Wrestling and wrestled at the TNA Pay-Per-View Victory Road 2004 as part of the 20 man international invitational, he was eliminated and the Tournament went on to be won by fellow luchadore and former LWO member Héctor Garza.

In 2005, Castellanos signed a contract with WWE. He appeared at the WWE-promoted ECW One Night Stand 2005 PPV on June 12, 2005 losing to Rey Mysterio, and first appeared on WWE television on the June 18, 2005 airing of WWE Velocity, teaming with Super Crazy to defeat Akio and Billy Kidman.

Psicosis, Super Crazy, and Juventud would group together to form a stable known as The Mexicools. The group made their debut as heels on June 23, 2005 when all three members rode to the ring on a John Deere lawn mower, with the sticker saying Juan Deere to be more Mexican, wearing matching coveralls and attacked both participants of a Chavo Guerrero and Paul London's WWE Cruiserweight Championship match.

Juventud cut a promo questioning the lack of "true Mexican Luchadores" in the cruiserweight division, before going on to deride the current state of Mexican Americans in general. Psicosis dubbed the lawnmower they arrived on a "Mexican Limo 2005" and the group claimed that even Mexico's President mocks Mexicans in the United States (he was referring to Vicente Fox's controversial remark that Mexican immigrants do the jobs "not even the blacks want to do"). Juventud then stated that they were "no longer there to clean toilets and work for "them" (the "gringos") but "they" were going to be working for "us" (The Mexicools)", before dubbing the team "not Mexicans but Mexicools!" In the following weeks, they would continue to interfere in matches and mock the stereotypical image of Mexicans in the United States, even coming to the ring each with their own riding lawnmower.

On July 24, 2005 at the Great American Bash in Buffalo, New York,in a match against the members of the bWo in a six-man tag match, the group pinned Steven Richards to secure the Mexicools' first PPV win. The trio then turned face by feuding with Nunzio and Vito.

During the December 2, 2005 edition of SmackDown! Super Crazy and Psicosis competed in an over the top rope battle royal against 5 other tag teams, the pair managed to win and earned themselves a match against MNM at Armageddon 2005 for the WWE tag team titles, unfortunately for the Mexicools, MNM lost the tag team titles before their match.

During the January 27, 2006 edition of SmackDown! Super Crazy and Psicosis defeated The Dicks and the F.B.I. in a three-way tag team match to win spots in the 2006 Royal Rumble match on January 29, 2006. During that same Royal Rumble match, Psicosis entered at Number 4, but was quickly eliminated by Rey Mysterio.

During mid-2006 the ECW brand was redeveloped and with this came the expectations that Super Crazy would leave Psicosis, and SmackDown!, for the new ECW. This was later fueled with a match that would see Yoshihiro Tajiri and Super Crazy team up and face the F.B.I. at ECW One Night Stand 2006. At this time, Psicosis's partnership with Crazy began to crumble when Psicosis repeatedly abandoned Crazy during incidents with The Great Khali. The team would soon split with Psicosis turning heel. Psicosis' match against Super Crazy on July 21, 2006, in which he lost, would be his last televised WWE appearance.

Psicosis's release was posted on WWE.com on November 1st, officially releasing him from his contract.

Psicosis is currently working as Nicho El Millionaro in Consejo Mundial de Lucha Libre (CMLL). At the end of 2006, he accidentally shattered his nose in a match against Hijo del Misterio, and also got his head shaved. He was rushed to a nearby hospital to get his nose set following the match.

On the March 3rd, 2007 televised episode of AAA, Psicosis came as Nicho and started a fight with Cibernetico. He had worn a La Parka mask pretending to be him in order to get La Parka expelled from AAA.

Psicosis was arrested on Monday, October 9, 2006 the night after he allegedly stole a car from 23 year old Alexander Valencia Ramirez of Playas de Rosarito, Baja California, reports Mexican newspaper El Mexicano.

The newspaper story claimed that Psicosis asked to borrow Ramirez's black Mitsubishi, promising to return it later that night. Ramirez refused, leading to Psicosis pulling a gun on him and taking the car anyway. Ramirez called the police who set up roadblocks around Rosarito. Psicosis hit several cars while in the chase including one that had a pregnant woman inside. After catching him, police found out that the gun he used earlier in the night was actually just a water gun.